The 2009Montreal Alouettes season is the 43rd season for the team in the Canadian Football League and their 55th overall. The Alouettes won their sixth Grey Cup championship, 28–27 against the Saskatchewan Roughriders, in a game the Montreal Alouettes trailed throughout, as they came back from trailing 27-11 four minutes into the fourth quarter. It was their first win since 2002, and it ended a streak of four Grey Cup losses in their last four appearances.

The Alouettes finished in first place in the East division setting a new franchise record of 15–3. It was the first time a team finished with a 15–3 record since the 1997 Toronto Argonauts.